rxsexen

hi Howard, quick question i live in sydney australia and the roads here are bad REALLY BAD to compensate i was going to purchase a coilover kit with a 7kg front and 4 or 5kg rear on 18 by 8.5 and 18by 9.5 what are you thoughts on this set up

Howard Coleman

iTrader: (6)

i like your staggered wheel setup, the FD needs more rear than front grip

the FD has 74% of the front spring rate (measured at the springs, not wheels) in the rear. i like to start at that balance. so will you.

so 7 KG X .74 = 5.19.

go w the 5 KG rears.

regards,

howard

rxsexen

also Howard another quick question what is the difference between mono shock and dual shock???and what benefits are there for wider dimention shock absorbers i.e 44mm 46mm??
Thank you

ITR

iTrader: (1)

Hi Howard. First and formost many thanks for all the input and help that you've given us!!

Are the figures for alignment listed on your first post (relisted below) good for an almost standard fd? (Mine has 18'' Rims 8''Front and 9''Rear with 225 and 255 tyres respectively and Apexi TMax suspension (Not coilovers)

Measurements listed in your first post:
Toe in front between a 1/16 and 1/8th inch
Toe in rear zero
Camber front and rear 1.2 degrees negative
Caster equal minimal
Zero rear thrust angle.

Thanks again.

Ken

Monkman33

iTrader: (28)

This is just an odd thought,

But wouldn't keeping the stock rubber shock mount be important to avoid putting undue stress on the shock itself in directions other than straight against the mount? Considering how much the whole assembly moves, unless you have solid bushings everywhere else, I would think that small amount of give from the rubber shock mount would actually be healthier for the shock itself? Just brainstorming and probably over-thinking, please correct me if I am wrong.

TURSTY

Hi Howard, I have just finished getting my race car going and now want to work on the suspention setup. The car (FD or course) is a track only (well, track MOSTLY) car so no need to worry about comfort. It runs 18x10 rims all round with the same offset (so the front track is slightly wider then the rear) with 265 semi slicks on all 4 corners.

With this increase in grip over stock, are you able to suggest a starting point for spring rates and possibly wheel alignment/ride hight if it would differ from your first post?

Im sure you have answered this question before somewhere in the last 31 pages, but I couldnt seem to find it after a VERY quick skim of them.

Thanks in advance for your help. Sam

GASnGO fd

hi howard,thanks for the awesome write up on fd suspension,we are setting up our s7 rx7 for street/track duties and was wanting to know a few things,i have factory rx7 16 inch rims with 225/50/16 toyo r888 semi slicks,tyre pressure cold is 25/26psi is this ok?all round, hks adjustable suspension,not sure of the spring rate, but will find out,and front /rear strut braces, would the set up you have in the first posts work with factory rims,ie,

toe in front between 1/16 & 1/8th inch
toe in rear <zero>
camber front &rear 1.2 degrees negative
caster equal\minimal
zero rear thrust angle

i will fit the bushings above the diff and the 2 sets on the lower link as well. over here in new zealand theres a class of rx7s that run on various tracks and the 3rd generation 7s use the factory rims,they are pretty lite and easy to get hold of,i have a set of 19inch rims that were on the car when i brought it but dont like them much for driving on,to much bling bling for my liking and heavy,so will just keep the standard rims on as i have two sets of 16 inch rims with semi slicks,thanks,les...

Howard Coleman

iTrader: (6)

F1 in HD.... lessons in plain sight

i'd prefer this thread not turn into an F1 thread but i was watching Spain Qualifying and some items jumped out at me that i thought would add something to the FD-world.

my first year of road racing was in open wheel formula cars and i still remember how neat it was to be able to see the tires work. (it was also really easy to place the tire exactly on the inside apex of the corner).

w the onboard F1 cameras, especially in HD, you can really really see the tires work.

first off, if you see shots of the cars it is clear they are running around a degree plus of negative camber in the front and almost no camber in the rear. this squares w my suggested setup.

from onboard you can watch the tire work thru a corner. you can see that the outside tire as the car turns in has a primary working surface that starts at the inside of the tire's lateral contact and then travels across toward the outer section as the corner progresses. really neat to watch.

a major diff between F1 and FD is downforce. since they develop a lot of it the spring's function is entirely different. it's primary function is to resist ride height change in the face of multiple Gs of downforce.

the FD spring's primary job is to provide a max of 2 inches (at the wheel) of bump travel.

back to F1...at high speed going straight the front tires are making more contact on the inner 1/3 producing less drag. (not to say the outers aren't making contact, just less pressure outer)

note that tire warmers are key. the cars go out and make immediate hot laps in qualifying. if your tires aren't up to temp you are going to go slow. (it generally takes 2 laps to get up to temp w an FD)

i use tire softener and that makes the tire sticky in the first lap (wears off at the end of lap 2 but by then the tires are up to temp)

so don't expect to go fast on laps 1 and part of 2.

note how the tire contact width is exactly the same as the rim width. you don't want tires bigger than your wheel...

i run 255s w 9.5 fr and 295 10.5 rear

one of the qualifiers was understeering in Q1. F1 prohibits setup changes BUT allows tire pressure adjustments. so in the rarified Tech-air of F1 what did they do? took some air out of the front tires.

speaking of tire pressures...

i was at Road America w a friend a couple of weeks ago. it was 55 degrees. i brought my air pressure gauge and pyrometer.

by adjusting (lowering) his tire pressures (over 10 psi) over a few sessions we had him running 20 seconds (4 mile track) a lap faster and he remarked the car was easier to drive.

ah, lowly tire pressures really are King.

his tire temps averaged 103 degrees so there is alot more speed to be had as summer arrives.

the pyrometer will tell you not only camber, toe, spring. swaybar info (actually EVERYTHING) but will tell you if a tire should have more or less air pressure. you are blind without a pyrometer and pressure gauge.

i invite anyone to post their tire temps and pressures and we can do some tweaking together.

BTW, as someone who turned off F1 15 years ago due to a lack of racing/PASSING i suggest you take a look this year. i happened to bump into the Turkish GP a few weeks ago and was blown away. a very very racey race w lots of passing. it appears they have solved their problem and are back to racing.

howard

fd_neal

iTrader: (4)

My experiance is this,
counterclockwise roadcourse, 2 major brake zones.

Old setup; 245/45/16 kumho v710 on factory wheels (or BFG R1's, but didnt like this tire at all). alignment was -1.6* front -1.2* 6.5* caster 0 toe front and rear. 10kg/8kg springs, factory swaybars. 25.5"F and 26.25"R rideheight. The car was very neutral with on throttle oversteer, front tire wear was good but not perfect, would wear the outside edge a little quicker, I would kill the outside edge of the outside rear tire. no tire temps for this setup.

New setup; 275/45/17 kumho v710 on 10" wheel 52 offset. Alignment -1.9L/-2.0R front -1.5L/-1.6R rear camber, 5* caster, 1/32 toe out front, 1/32 toe in rear. Racing beat sway bars, same 10kg/8kg springs. 25.25" rideheight all around. Ive only been out on this setup once but in the higher speed brake zone (240 - 140kmph) the car is unsettled but controllable (probably front toe out and less caster), turn in is night and day better over the old setup (front toe out, less caster, more bar, and more tire), corner exit im not spinning tire nearly as much (more tire) and the car feels well balanced but I didnt push it that hard as it was a test and tune night on stickered tires. Tire temps were dead even across all tires except the outside rear was 20* hotter than the rest.

For a square setup I would use more front negative camber ~.5 degree works for me so far. For Rcomps or slicks I would generally set camber with the tire manufactures recomendation in mind, for an FD I would run less than they recommend as we have good camber curves, but bring a pyrometer for fine tuning (Im glad I picked one up for this season! Im sure this tool will help me find some more time on track)

koan123

Howard I would like to thank you for providing such a wealth of knowledge!

While I'm too young to get into a FD yet (insurance in the UK is a nightmare) you've given me a substantial amount to think about regarding the set up of my MX-5.

When I get back to the track I'm definatly taking a pyrometer with me! With any luck I should stop burning up my T1R's so quickly (good all round tyre despite the soft sidewalls, mush on track).

All the best, Mark

Howard Coleman

iTrader: (6)

bumped into an interesting article in Grassroots Motorsports this month...

don't you just hate it when someone ACTUALLY TESTS THEORIES?

light wheels V heavy

fat tires V thinner tires.

the executive summary was

maybe lighter wheels are good for the slightest of advantage.

tires w contact patches larger than the rim width are SLOWER and HARDER TO DRIVE.

as you may remember my post one suggests run tires w a contact patch no larger than rim width. (i also mentioned this in my above post in relations to F1.... but what do they know.)

the speed differential between fatter tires and tires the width of the rim was quite a bit in racing metrics.... 53.65 seconds V 53.13.

wheel was 17 X 9

tires were 245 40 and 255 40
contact patch was 8.8 and 9.1

"The narrower and shorter 245 tires felt more nimble, allowing both drivers to place the car closer to the cones with complete confidence. Turn-in was sharp, acceleration felt noticeably better, and when it came time to throw out the anchor, the car felt as if it slowed more quickly. It seemed the narrower tires simply offered more precision and communication.

In comparison, the wider tires felt a little lethargic in quick transitions. They also had an elastic feel when accelerating away from faster corners, often transitioning to gentle power-on oversteer as rear end breakaway was hard to anticipate." GRM


key words from above:

precision
communication

i would add linearity and you have what you need to go fast.

i run a 9.5 rim in the front w a 9.1 tread width.

i run 10.5 rear w 10.6 t w.

don't go too big for your rim width or you will be doing the elastic fantastic.

howard

$lacker

iTrader: (9)

For tire pressure (30 front 27 rear), is that a decent setup for autocross on a performance street tire as well? Or just a race track?
Everyone is telling me that on performance streets I need 40-45lbs of pressure for autocross, but they don't have the sort of experience that some of you guys do
Thanks

$lacker

iTrader: (9)

Fwiw- in our autocrossing, I don't imagine the tires ever get properly "up to temperature"

$lacker

iTrader: (9)

Sorry for all the posts... it won't let me edit to add things :P

You say "I run my front shocks 7 clicks from full soft and my rear 2 clicks from full soft" and that your Teins have 16 settings? So does it stand to reason that with my HKS Hipermax coilovers (and their 30 settings) I would go 14 from full soft and 4 from full soft respectively?

Thanks Howard

Howard Coleman

iTrader: (6)

"does it stand to reason that with my HKS Hipermax coilovers (and their 30 settings) I would go 14 from full soft and 4 from full soft respectively?"

sure, you could start there but unfortunately there are lots of other variables and i have never dynoed the Hipermax so i am the wrong person to ask.

rxetera

I noticed that this thread has no comments on the various chassis stiffening products currently available. I'd like to know how much of an effect items like fender braces, member braces (Autoexe) etc would have on handling response.

Given that most dedicated racers get this benefit from a full rollcage, I'm interested in whether these other products would aid a dual purpose vehicle?

Brekyrself

iTrader: (30)

Great question. Coming from the e36 M3 world, most of the folks who competitively raced their cars would always argue strut braces with hinges were worthless. The idea is that with a hinge, one strut tower could lift and the strut bar would just pivot at the hinge point.

They would always recommend a solid bar such as this:
http://m3forum.net/m3forum/showthread.php?t=355092

Thoughts?

BADSVN2000

Hey everyone! so I have read this entire thread and what a world of information! Thank you so much Howard this has been a huge help!

So my set up is the Tein Super Street coil overs from Japan, stock front and rear sway bars, 17x8 and 17x9 Gram Light wheels and 235/45/17 RE070 fronts and 255/40/17 RE01R's on the rear. I have not managed to replace any of the old bushes as yet due to lack of funds but im getting there......

My car was riding 24" in the rear and just under 25" in the front and today i decided to set it up properly based on Howards advice.

I re-set the ride height and found that both front and rear shocks had been set at the lowest level, i.e. springs were not even captive as locking rings were sitting at the bottom of the thread. Please take note that i got these second hand but near new condition and have barely touched the car in a year since they were installed.

Anyway, back on track... my car was very bouncy before i was accelerating in 3rd gear on the motorway, hit a bump and the car spat out sideways as the rear wheels lost traction. It was at this point i realised i needed to sort my suspension out seeing as I now had 410HP at the wheels and i didnt really want to kill myself anytime soon... so i now have 25" (635mm) ride height on all four corners, my camber has been adjusted to -1.5 degrees and my toe as per Howards reccomendations please see the attached wheel alignment sheet.

I am wanting to do more track work, i barely drive the car on the road but yes it is still a street car with full interior.
The question i have, which i have not picked up in this thread is: Seeing as my goal is to track it more often should I increase the camber to -3 front and -2 rear as i picked up in earlier posts and if so do i need to alter the toe settings to suit the increased amount of camber and if so how do i figure out what is a good setting? and do i need to adjust the caster too?

I am guessing that the reason that my car was so bouncy was because the shocks were bottoming out and by raising it up the ride is so much better and with the alignment, far more responsive in the handling deptartment. I will be having another wheel alignment in the next week or two as i found i have a bent rack end......

anyway here is the printout from my alignment today.. I would like to hear what some of you have to say about it.

Thanks for all of your input this far everyone!

GodSquadMandrake

Your shocks aren't from Japan, Tein is made in Taiwan like most others.

If you read the article then you know that Howard isn't recommending specific camber settings. He is recommending to take temperature measurements to determine if the temperature is even across the entire surface of the tire. That means taking readings with a probe in 3 places. The inside, middle and outside of the tread. If those three readings are even after a hot lap, then your camber is fine. If the inside is too hit, you have to much camber. If the outside is hot, you don't have enough.

BADSVN2000

Ok thanks, i was unaware they were made in Taiwan but that's besides the point and I was referring to the post where someone said that the US and Japan/UK versions came with different rated springs....

I will leave my camber as is for now and try to get my hands on a pyrometer for the next track day and go from there... i understand that no track is the same so not one set up can be applied across the board for all tracks. I just dont have all the gear to be able to do an accurate re-alignment at the track.

CYD

Ok, so clearly getting tire widths matched up to the wheel width is key.

What about the difference between 18x10 vs 18x12 with properly sized tire widths to those wheel widths?

Was there any note on running a wider wheel + tire vs a skinnier wheel + tire?
Or am I missing that in your post? I have seen a number of 18x10 fronts and 18x12 rears, and even a 18x12 front and rear. So given the proper tire with the wider wheels, is that ill advised in terms of slower/harder to drive or elastity-fantatty?

~CYD

IWINULUZ

iTrader: (10)

I know this thread has been beat to death but i would like a little more in depth explanation as to the mathematics that go into the tire equation. e.g

25.4mm = 1 inch. (for the noobs )

9.5 rim width = 241.3mm width (which would make sense to me to run a 245 not 255)

10.5 rim width = 266.7mm width (" " " " "" "" 265 not 295)

i am only questioning this because i am trying to decide if i should downsize my rear tires (which are now 295's on 10" wide rim)

I know there is a fine line between grip and rotating weight and want to find a good equilibrium between the two. From out of the hole to higher speeds. (leaving contact patch out of the equation; simply because it would never end lol) I am looking to go with a street dry performance tire with decent wet traction but weekend track warrior, it looks like might consider the Yokohama Advan A048 (6/32's sucks, but function > longevity) 235/40/18 & 295/30/18 unless you think i should run something less agressive i.e 275/35 only problem is that overall diameter is closer to OE with the 295/30 than any other option. and no one makes 275/30 (as specified in "jimlab's" FD Wheel/tire sizing chart.)

So any insight into this equation (if there is one) would be sincerely appreciated.

-Jason

rxetera

I wasn't referring to strut braces, rather fender braces, and underbody bracing. The idea is that the stiffer the fender area, the quicker any changes can be imparted to the driver's seat. The question I have is whether this also improves lap times significantly? Most who have installed it say the feel is better, but I've never heard any accounts of improved lap times.

TURSTY

Hi Howard,

I am looking into purchasing coilovers and improving the overall handeling of the car again and have decided to go with 10/8kg springs and independant height adjustable coilovers.

My question now is more around swaybars for a track only car. Its not exactly easy to get these in NZ, but there is a set of Cusco bars available that list as Front - 139% stiffer and rear - 250% stiffer.
After reading most of the pages on here these sound like they are WAY up on what you have recomended. On a full track car, running 265 semis all round on 18x10" rims, are you able to explain what effect bars this stiff would have? Im guessing there will be issues with lifting inside wheels and loosing overall grip?

Im also looking into adjustable A arms - that being said, would you recomend running the car as low as it can while still retaining the 2" of travel and say a .5" as a buffer? (taking into account of course the clearance of the front bumper under brakes etc etc.). What would you recomend, and why (im really interested in learning as much as I can, but I am still new to this =P)?

Another question I have also been wondering about is spring preload. Does adding static preload to the springs act the same way that installing a stiffer spring would? Any chance you could touch on this?

adamrs80

iTrader: (7)

Can anybody confirm that the Eibach Pro Kit springs are NOT discontinued? I found a Pro-Kit for the FD RX-7 on their website with part #5525.140.

I've been able to find them online for sale at advanceautoparts.com and other places.

http://www.redlinemotive.com/part-nu...h/5525.140.asp

Can somebody tell me if this is the same spring kit that has been referred to numerous time throughout this thread discussion?